United States Patent Publication Number 2008/0026095 discloses an injection molding machine includes an injection unit and a clamping unit. The injection unit includes a barrel and a plasticizing screw which is supported in the barrel for rotation and movement in axial direction. A first direct drive causes the plasticizing screw to rotate in order to plasticize thermoplastic material, and a hydraulic drive causes the plasticizing screw to move axially in order to effect an injection stroke. The hydraulic drive includes a hydraulic accumulator system which is comprised of a variable capacity pump in combination with a hydraulic accumulator. The clamping unit includes a toggle mechanism for moving a movable platen in relation to a stationary support platen, a spindle mechanism for operating the toggle mechanism, and a second direct drive for operating the spindle mechanism
United States Patent Publication Number 2007 0194474 discloses an injection press that has a hydraulic cylinder and a press piston located inside the hydraulic cylinder that is translatable within the cylinder. The press piston divides the hydraulic cylinder into engage and retract chambers. A pump and an auxiliary pressurization device are connected to the engage chamber. A transducer measures the pressure in the engage chamber. A controller receives signals from the transducer and operates the pump. The pump delivers hydraulic fluid to the engage chamber to pressurize and inject resin into a mold cavity through the piston. The controller discontinues operation of the pump when the pressure in the engage chamber reaches a specified cut-off level. The auxiliary pressurization device maintains pressure on the fluid in the engage chamber after the controller discontinues operation of the pump to provide back pressure on the injected resin. The auxiliary pressurization device may be an accumulator that is charged by the pump. Safety devices prevent the controller from operating the pump during unsafe conditions.